The Dutch pilots’ association VNV has spoken out against plans to scrap or scale down the co-pilot’s role, calling it an “irresponsible and unnecessary gamble with air safety”.

The EU Aviation Safety Agency (EASA) has commissioned a study into the feasibility of single-pilot planes, which is due to be published this summer, while aircraft manufacturers such as Airbus and Dassault are already working on planes that are designed to be flown by one person.

Hong Kong-based airline Cathay Pacific is rumoured to be looking at cutting the number of pilots on its Airbus 350 planes from four to two for long-haul flights, with only one person in the cockpit for most of the journey.

EASA is studying two scenarios: one in which a co-pilot assists with take-off and landing but is not required for the rest of the flight, and another which would see a single pilot fly the plane with support from a crew member on the ground or technological assistance.

But pilots say the move will compromise passenger safety because co-pilots are better able to respond to sudden or unexpected developments during the flight. A single pilot would also be more vulnerable to incidents on board, such as a hijacking.

“What if the pilot suddenly feels unwell? Then you’re glad that there are two pilots up front,” VNV chairman Camiel Verhagen told NOS.

“Or imagine the pilot needs the toilet. Should they keep an eye on the plane with their trousers round their ankles, or is there nobody at the controls? Taking a pilot out of the cockpit won’t improve any safety issues; in fact it will create one.”

Dutch national airline KLM said it currently had no plans to introduce single-pilot flights. “Safety always comes first for us,” said a spokesman. “That’s why KLM is following the research with interest and waiting to see the results.”